The present invention relates to a safety circuit for electronic velocity control or regulating systems for motor vehicles with idling control, in which a setting device for the power of the engine of the motor vehicle can be fed with a desired value and the setting device comprises a setting controller, an output stage and a setting member.
Velocity control systems for motor vehicles comprise, inter alia, an electromotive setting member, a quick-separation clutch and an underlying position control circuit which brings the electromotive setting member into the predetermined position corresponding to the command given by a controller. For reasons of safety, a disconnect device is provided which prevents an opening of the throttle valve when the velocity control system is off. Since the opening of the throttle valve is then not to be prevented merely temporarily, the disconnect device has storage properties, for which reason it is also referred to as a disconnect memory.
Similar safety devices are provided in so-called E-gas (electric gas) systems in which the position of the throttle valve is controlled on the basis of a command (electric signal) given by the accelerator pedal.
There are also known for motor vehicles devices for controlling the idling speed of rotation, wherein an air feed parallel to the throttle valve is controlled. This, however, means an additional expense, which can be avoided if the throttle valve is also used for controlling the idling. However, this is not possible in connection with the known E-gas systems and velocity control systems since, in the event of disconnect, an opening of the throttle valve is made impossible.
It is an object of the invention to propose a safety circuit for electronic velocity control or regulating systems for motor vehicles with idle control in connection with which, despite the fact that the control or regulating system is disconnected, actuation of the throttle valve for idle control is possible.